Watercraft with compressed air propulsion system

Abstract

A watercraft comprising a compressed air propulsion system is shown and described. The watercraft includes at least one propeller operatively connected to an air motor. Storage tanks supply compressed air having a pressure of at least 2000 psi to a pressure regulator that reduces the pressure and supplies air to an air control valve. User controls adjust the air control valve to adjust the flow rate of air to the air motor which in turn adjusts the direction and/or speed of rotation of the propeller. An on-board air compressor energized by a plurality of lithium iron phosphate batteries provides air to the air storage tanks when the pressure falls below a specified value. In certain examples, the electric and air propulsion system is used to replace a fossil fuel engine in an existing watercraft and can remain at sea longer than the existing watercraft.

What is claimed is: 
     
       1. A watercraft, comprising:
 a hull; 
 a propeller operable to propel the watercraft through a body of water; 
 an air motor operative to rotate the propeller; 
 an air storage tank in selective fluid communication with the air motor; and 
 an air compressor operable to selectively supply compressed air to the air storage tank wherein the air compressor is powered by at least one battery. 
 
     
     
       2. The watercraft of  claim 1 , further comprising:
 an air control valve having an inlet in fluid communication with the air storage tank and an outlet in fluid communication with the air motor, wherein the air control valve is adjustable to adjust an air flow rate to the air motor, thereby adjusting a speed of rotation of the propeller. 
 
     
     
       3. The watercraft of  claim 2 , further comprising a pneumatic control unit comprising the air control valve, and at least one lever operable to adjust a flow rate of air to the air motor and move the watercraft in forward and reverse. 
     
     
       4. The watercraft of  claim 1 , further comprising:
 one or more accessory batteries electrically connected to at least one selected from a horn, lights, and a radio; 
 a propeller shaft having a first end and a second end, wherein the first end of the propeller shaft is coupled to the air motor and the second end of the propeller shaft is coupled to the propeller; 
 an alternator connected to the at least one battery and the propeller shaft and operable to charge the one or more accessory batteries when the propeller shaft rotates. 
 
     
     
       5. The watercraft of  claim 1 , wherein the at least one battery is at least one lithium iron phosphate battery. 
     
     
       6. The watercraft of  claim 1 , wherein the at least one battery comprises a plurality of lithium iron phosphate batteries. 
     
     
       7. The watercraft of  claim 1 , further comprising:
 four primary lithium iron phosphate batteries, wherein the four primary lithium iron phosphate batteries include the at least one battery; and 
 ballast comprising a plurality of spare lithium iron phosphate batteries having a collective weight of at least about 500 lbs. 
 
     
     
       8. The watercraft of  claim 1 , wherein the watercraft does not include a fossil fuel engine or fossil fuel tanks. 
     
     
       9. A watercraft, comprising:
 a hull; 
 a propeller operable to propel the watercraft through a body of water; 
 an air motor operative to rotate the propeller; 
 an air storage tank in selective fluid communication with the air motor; and 
 an air compressor operable to selectively supply compressed air to the air storage tank, wherein the air storage tank is a master air storage tank, the watercraft further comprising a slave air storage tank, wherein the master air storage tank has an inlet line and an outlet line, the slave air storage tank has an inlet line and an outlet line, the compressor has a discharge line in fluid communication with the slave air storage tank inlet line, the slave air storage tank outlet line is in fluid communication with the master air storage tank inlet line via a pressure drop valve, and the master air storage tank outlet line is in fluid communication with the air motor. 
 
     
     
       10. The watercraft of  claim 9 , further comprising a low pressure switch fluidly coupled to an interior volume of the slave air storage tank and operatively connected to the air compressor, such that when a pressure in the slave air storage tank falls below a first specified threshold value, the air compressor is activated to perform a slave air storage tank air refilling operation until the pressure in the slave air storage tank reaches a second specified threshold value. 
     
     
       11. The watercraft of  claim 10 , wherein the first specified threshold value is from about 1500 psi to about 2500 psig. 
     
     
       12. A watercraft, comprising:
 a hull; 
 a propeller operable to propel the watercraft through a body of water; 
 an air motor operative to rotate the propeller; 
 an air storage tank in selective fluid communication with the air motor; and 
 an air compressor operable to selectively supply compressed air to the air storage tank, wherein the air compressor has a maximum air discharge pressure of about 5000 psig. 
 
     
     
       13. The watercraft of  claim 12 , wherein the air storage tank has an outlet line fluidly coupled to a pressure regulator, the watercraft further comprising an air control valve in fluid communication with the air motor and the pressure regulator, wherein the pressure regulator is set to provide air to the air control valve at a pressure of no greater than 500 psig. 
     
     
       14. A watercraft, comprising:
 a hull; 
 a propeller operable to propel the watercraft through a body of water; 
 an air motor operative to rotate the propeller; and 
 an air compressor operable to supply compressed air to the air motor, wherein the watercraft does not include a fossil fuel engine or a fossil fuel tank, and wherein the air compressor is electrically connected to at least one battery. 
 
     
     
       15. The watercraft of  claim 14 , further comprising a pneumatic control panel comprising an air control valve, and at least one lever operable to adjust a flow rate of air to the air motor and move the watercraft forward or in reverse. 
     
     
       16. The watercraft of  claim 14 , further comprising:
 one or more accessory batteries electrically connected to at least one selected from a horn, lights, and a radio; 
 a propeller shaft having a first end and a second end, wherein the first end of the propeller shaft is coupled to the air motor and the second end of the propeller shaft is coupled to the propeller; 
 an alternator connected to the one or more accessory batteries and the propeller shaft and operable to charge the at one or more accessory batteries when the propeller shaft rotates. 
 
     
     
       17. The watercraft of  claim 14 , wherein the at least one battery is at least one lithium iron phosphate battery. 
     
     
       18. The watercraft of  claim 17 , wherein the at least one lithium iron phosphate battery comprises a plurality of lithium iron phosphate batteries. 
     
     
       19. The watercraft of  claim 14 , further comprising:
 at least four primary lithium iron phosphate batteries, wherein the at least four primary lithium iron phosphate batteries include the at least one battery. 
 
     
     
       20. A watercraft, comprising:
 a hull; 
 a propeller operable to propel the watercraft through a body of water; 
 an air motor operative to rotate the propeller; 
 an air compressor operable to supply compressed air to the air motor, wherein the watercraft does not include a fossil fuel engine or a fossil fuel tank; 
 a master air storage tank in fluid communication with the air motor, wherein the compressor is selectively operable to supply compressed air to the master air storage tank; and 
 a slave air storage tank, wherein the master air storage tank has an inlet line and an outlet line, the slave air storage tank has an inlet line and an outlet line, the compressor has a discharge line in fluid communication with the slave air storage tank inlet line, the slave air storage tank outlet line is fluid communication with the master air storage tank inlet line, and the master air storage tank outlet line is in fluid communication with the air motor. 
 
     
     
       21. The watercraft of  claim 20 , further comprising a controller and a low pressure selector fluidly coupled to the slave tank and the controller, wherein the controller is operatively connected to the air compressor, such that when a pressure in the slave tank falls below a first specified threshold value, the air compressor is cycled on until the pressure in the slave tank reaches a second specified threshold value. 
     
     
       22. The watercraft of  claim 21 , wherein the first specified threshold value is from about 1500 psig to about 2500 psig. 
     
     
       23. A watercraft, comprising:
 a hull; 
 a propeller operable to propel the watercraft through a body of water; 
 an air motor operative to rotate the propeller; and 
 an air compressor operable to supply compressed air to the air motor, wherein the watercraft does not include a fossil fuel engine or a fossil fuel tank, and wherein the air compressor has a maximum air discharge pressure of about 5000 psig. 
 
     
     
       24. The watercraft of  claim 23 , wherein the air storage tank has an outlet line fluidly coupled to a pressure regulator, the watercraft further comprising an air control valve in fluid communication with the air motor and the pressure regulator, wherein the pressure regulator is set to provide air to the air control valve at a pressure of no greater than about 500 psig.